1. Field of the Invention
The present invention relates to a key input device for visually observing display data displayed on a display unit through a keyboard.
2. Description of the Prior Art
In an input/output device having a transparent keyboard as an input device arranged on an upper surface of a display unit as an output device, the transparent keyboard as the input device has two transparent sheets spaced by a small distance apart from each other, transparent electrodes are formed on the opposing surfaces of the two transparent sheets, and a key input entered such that the upper transparent sheet is depressed by a finger so as to bring the opposing transparent electrodes into contact with each other. A display unit as the output device is arranged under the transparent keyboard. Characters and numerals displayed on the display unit under the transparent keyboard are observed while an operator enters desired information. However, when a spacer is not inserted between the two transparent sheets constituting the transparent keyboard, contact electrodes of the neighboring keys on the upper transparent sheet are brought into contact with the corresponding electrodes of the lower transparent sheet even if a given key is depressed. In other words, even if the operator enters a single key signal, a plurality of key signals are entered in practice, resulting in data entry errors. However, when the spacer is inserted between the two transparent sheets, it is difficult for the operator to read the characters and numerals displayed on the display unit, resulting in inconvenience.